存储在blobstore中的PPT等文件在网页中怎么通过iframe预览？

[qq_15201933]

在application的Dashboard中，Blob Viewer下点击某一具体的文件就可以预览：

源代码是：
<iframe src="https://appengine.googleusercontent.com/blobviewer/f604b90b0bec805e2c2ed49955642f5c5b4f2ce1/d8b6835924153957612be73f3d7eb31fcce6de85/2015-05-12T12:59:52/s~chemistry-graduation-design/-/AMIfv96F-zDFi5LHzllVsGlJInL5PaRA_A7TpH60S6jqWuZwRs17VW3RfcuechIJywjx7rcgxgycNlWywGO-esan8JcUTBr5bwzTpTcaXcv-Sj-Qp8gdjF70VapTBKidJma6KQ5-ifqF1-AMjHNIDXFrx6uNKAo9bML9WlFmPrAQd4f5iXUAvHo"
width="100%" height="400" scrolling="auto" frameborder="1">

在自己的网页里网址怎么写呢，我知道最后一段是blob-key